okl 0.8.6

• A prompt with no text briefs nothing. An image or a file sent alone reached the prompt
  hook as an empty prompt, and the hook briefed the last commit's subject instead: twelve
  lessons about unrelated work. The hook now says there is nothing to brief on, to the
  agent and the person, without asking okl (an okl before this release answers an empty
  task with every lesson). OKL_TASK still overrides, and a run with no prompt event at
  all keeps the last-resort task.

• A prompt with no subject is no longer briefed (okl review R7, #178). Every word of a
  prompt was OR-ed into the briefing's search, so "ok go", "do it" or "what about this one?"
  matched enough of a store to fill the 12-lesson cap. The briefing now searches on the
  prompt's subject words: single characters and a curated list of function words and chat
  filler are left out, each term counts once, at most 40 are used, and a prompt with no term
  of three or more characters briefs nothing. Short subject tokens such as id, ci and
  db, and get, are kept, and so is a filler word inside a dotted name, so "Next.js" still
  briefs. okl search is unchanged. An empty prompt also no longer falls
  through to a search that matched every lesson.

• A precision check for the briefing (okl review R8, #179). evals/precision.py scores 30
  filler prompts on a store built only from the seed packs git tracks, and fails when one
  briefs more than 3 lessons: before this change 18 did, 12 of them at the cap; now none.
  It also reports which lessons take the most slots. REPORT §4l pre-registers the A/B run
  this retrieval change needs before it ships.

• A one-page overview at the top of "How it works". Guardrails and a learning loop on one
  page, in light and dark, rendered from docs/overview/okl-overview.html; the detailed
  diagram stays below it. ci/check-diagram-figures.sh now reads HTML diagram sources too.

• The README's comparison credits the neighbours that do invalidate. It said mem0, Zep,
  Letta and Cognee let memories accumulate; Zep closes a contradicted fact on a timeline and
  mem0's model updates or deletes one. Utopia, an enterprise bitemporal knowledge graph, is
  added. What none of them does is tie a memory to your code, which is the row's point.

• The A/B judge reads the whole submission (#182). It read only the first 8,000
  characters, so a long submission reached it cut off mid-line: §4l lost a 15,585-character
  sample the judge called no code. It now reads up to 40,000 characters, a longer submission
  is unevaluable rather than judged on a cut copy, and each receipt records the window.
  REPORT §4m pre-registers the change of instrument.